Improvement in locks for fire-alarm boxes



.I. M. FAIRBHILD.

Looks for Fire-Alarm Boxes, 8w.

N0.144,079. PatentedOct.28,1873.

55% i @z i UNITED STATES PATENT OFFICE J. MURRAY FAIBCHILD, OF NEWHAVEN, CONNECTICUT.

IMPROVEMENT m LOCKS FQR FIRE-ALARM BOXES, ac.

Specification forming part of Letters Patent No. 144.079, dated October28, 1873; application filed July 9, 1873.

To all whom it may concern:

Be it known that I, J. MURRAY FAIRoHrLi), of New Haven, in the county ofNew Haven and State of Connecticut, have invented a new Improvement inTrap-Locks; and I do hereby declare the following, when taken inconnection with the accompanying drawings and the letters of referencemarked thereon, to be a full, clear, and exact description of the same,and which said drawings constitute part of thisspecifioation, andrepresent, in

Figure l,'an inside view of the look as set for trapping; and in Fig. 2,the same with the principal key trapped, and the releasing-key as in theact of freeing the trapped key.

This invention relates to an improvement in looks, particularly to thatclass in which the bolt is thrown out by a spring, yet applicable toother constructions; the object of the invention being to catch the keywhich may be inserted to draw the bolt, whether it be properly orimproperly introduced, and is to be applied to such positions where themisuse of a key is suspected; and the invention consists in combining,withtheprincipaltumblers, an auxiliary tumbler, which, permitting thekey to drawthe bolt, will, when the bolt is drawn, fall down on the bitand prevent the further-turning of the key; and also an auxiliary key,acting only upon the auxiliary tumbler, for the purpose of freeing thetrapped key.

A is the case (shown with the covering-plate removed B, the bolt; C, alever, against which the key strikes to throw the bolt, as denoted inFig. 2. The key is here represented as a pipe-key. One or more tumblers,D, are arranged upon a stud, E, combined with the bolt, and so as to beactuated by the key to permit the drawing or throwing of the bolt, as inlocks of common construction. F is an auxiliary tumbler, preferablyarranged upon the same pivot E, and is raised by the principal key,substantially as the other tumblers; but when the key has been turnedpartially over, a notch orshoulder, b, falls down upon the bit of thekey and prevents its further move ment. Therefore, as the key cannot beturned, it cannot be withdrawn from the lock, and is there securely heldby the tumbler F 5 and this will be the case whether the lock beproperly opened or not.

This lock is not designed for general uses of security, but is to beused where it is supposed the proper key or a duplicate issurreptitiously used, as in cases where many locks are used having thesame key. In such a case the lock commonly used is removed, and thislock, with the trap, attached, the same key which operated the originallock also operating the trap-lock. inserted to open the lock, itwill becaughtand held, as before described, and thus lead to the detection ofthe person who inserted the key. The object accomplished, the trap isremoved and the original lock replaced.

As a convenience for freeing the trapped key without opening the lock, Iprovide an auxiliary key, G, inserted through a second key-hole, H,preferably upon the opposite side to that in which the principal key isinserted. This key Gr operates upon the auxiliary or trapped tumbler F,so as to raise it, as denoted in broken lines, Fig. 2, and free thetrapped key.

I claim as my invention 1. The auxiliary tumbler F arranged to beoperated by the principal key, and to engage the bit of the said keyafter the bolt is withdrawn, and prevent its removal from the lock,substantially as described.

2. In combination with the auxiliary tumbler F, constructed to engagethe principal key after the bolt is withdrawn, the auxiliary key G, foroperating the said tumbler to free the principal key, substantially asdescribed.

' J. MURRAY FAIRCHILD.

Witnesses A. J. TreBrTs, J. H. SHUMWAY.

Therefore, when the key is

